Abbot is rarely used as a first name. Abbott and Costello were a very famous comedy duo (these were surnames though). Abbot sounds quirky. Such an unusual name will be easy to remember for new people.
An abbot is the head of a monastery. It is a shortened version of "Abbott." It is much more common as a family name (surname) than as a first name. The name probably comes from Hebrew, but is described as Old English.